Check valve necessary?

Dec 10, 2012 10 Replies

Hi all,



Can anyone enlighten me as to what a "check valve" is and do I need one per feed for the h/c supply pipes to a bathroom sink monobloc tap? The Screwfix catalogue says I need to use check valves for the flexible tap tails I plan to fit to replace the existing corroded rigid copper ones. Is that right? Both supply pipes come up from under the floor, BTW, and they already have isolators.



Thanks!


feed for the h/c supply pipes to a bathroom sink monobloc tap?

tails I plan to fit to replace the existing corroded rigid copper ones. Is that right? Both supply pipes come up from under the floor, BTW, and they already have isolators.

I think you would only need them on a basin mixer if one supply is mains pressure and the other is from a storage tank, to prevent cross contamination.

They don't work very well on low pressure supplies though - you may only get a dribble through.

er feed for the h/c supply pipes to a bathroom sink monobloc tap?

ap tails I plan to fit to replace the existing corroded rigid copper ones. = Is that right? Both supply pipes come up from under the floor, BTW, and the= y already have isolators.

A check valve is a one way valve. You might need one or even two on a mixer tap if the water pressures were unequal (often happens.) and the hot and cold water are actually mixed as opposed to having two separate spouts (as most have but not all) This stops cold water going into the hot water system and so causing the loft tank to overflow with hot water.

Thanks both, the pressures may well be a bit unequal, but there's no loft tank. The tap is a single stem mixer. Do I still need these valves?

feed for the h/c supply pipes to a bathroom sink monobloc tap?

tails I plan to fit to replace the existing corroded rigid copper ones. Is that right? Both supply pipes come up from under the floor, BTW, and they already have isolators.

The far greater danger is the possibility of 'contaminated' water which has been in the loft tank getting into the cold supply in the event of a mains failure.

a single stem mixer. Do I still need these valves?

Where does it get its hot water from?

is a single stem mixer. Do I still need these valves?

Condensing boiler in the kitchen.

In that case, if hot and cold are essentially at mains pressure - with cold coming direct,and hot via a combi boiler - I can't see how check valves would serve any useful purpose.

I think this may be useful if the combi boiler has a flow reducer which enables it to heat the cold water up. This would essentially mean that the hot water coming from the boiler will be at a lower pressure than the cold mains inlet. Cheers.

Maybe he has been in a black hole for a few years but it seems like only yesterday? Brian

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